As capacitance touch panels, there are two types, i.e. the surface type and the projection type. The capacitance touch panels are configured to specify a detection point by determining a change in capacitance which occurs when the surface of the touch panel is touched by an operating object such as a finger. The surface type can detect only one point at a time, whereas the projection type can specify coordinates of a detection point through determination of change in capacitance with utilization of electrodes which are arranged to intersect the X direction and the Y direction. For this reason, many electronic devices employ the projection type.
Further, the projection type includes a self capacitance type and a mutual capacitance type which differ in the method of detecting change in capacitance. The mutual capacitance type configured to specify a detection point directly when a change in mutual capacitance is detected through determination of mutual capacitance between an X electrode and a Y electrode is superior to the self capacitance type for multiple point detection applications. Therefore, electronic devices implementing a user interface contemplating multiple point detection employ the mutual capacitance type (see e.g. Patent Document 1).
Here, an electrode configuration of a conventional mutual capacitance type touch panel is illustrated in the schematic diagram of FIG. 9. As shown in FIG. 9, a touch panel 501 includes a plurality of lower electrodes 510 arranged parallel with each other along the X direction and a plurality of upper electrodes 520 arranged parallel with each other along the Y direction to intersect (perpendicular to) the respective lower electrodes. The upper electrodes 520 and the lower electrodes 510 are formed by etching a thin film made of a transparent conductive material (e.g. ITO, indium oxide, tin oxide, etc.) in the form of band-like electrodes separated from each other.
As shown in the schematic diagram of FIG. 10, the lower electrode 510 functions as a transmitter-side electrode, whereas the upper electrode 520 functions as a receiver-side electrode. When an object 200 such as a finger is not in contact with or not in the vicinity of the upper electrode 520 side, that is, the touch surface side, there is formed an electric field whose electric force lines L extend from the transmitter-side lower electrode 510 toward the receiver-side upper electrode 520. When the object 200 such as a finger approaches the upper electrode 520 to such an extent to affect the above electric field, some of the electric force lines L will travel around the upper electrode 520 to be absorbed by this object such as a finger. As a result, a change occurs in the mutual capacitance, and coordinates of this change can be detected as a detection point. Incidentally, in order to eliminate noise influence from LCD, the width of the lower electrode 510 is set wider than that of the upper electrode 520. Conversely, the spacing between adjacent lower electrodes 510 is set narrower than the spacing between adjacent upper electrodes 520.
Further, as a method of forming an electrode pattern in such a device as a flat panel display, a touch panel, a solar cell, etc., a commonly employed method is such that after a thin film made of transparent conductive material (transparent conductive film) is formed by the sputtering technique, a resist pattern is formed by the lithography and then a predetermined portion of the transparent conductive film is removed by the wet etching technique, thereby forming an electrode pattern.
In recent years, however, in consideration to costs or the like, attempts have been made to form a transparent electrode pattern with using a material other than ITO, indium oxide, or tin oxide (e.g. conductive ink containing conductive fibers such as silver nano fibers). For instance, in Patent Document 2, there is disclosed a method as follows. Namely, there is employed a photosensitive conductive film (dry film resist) comprising a conductive layer 12 containing conductive nano fibers and a photosensitive resin layer 13, which layers are laminated one after another on a support film 11. Then, the above resultant assembly is laminated on a substrate 45 with the photosensitive resin layer 13 of the assembly being placed in gapless contact therewith (FIG. 11A), after which the photosensitive resin layer 13 is exposed with irradiation of active beam L2 thereon (FIG. 11B) and then the photosensitive resin layer 13 is developed (FIG. 11C), thereby to form a photosensitive resin layer 13b and a conductive layer 12a in the form of a pattern.